Before using varenicline, tell your doctor if you have kidney disease, or a history of mental illness.
Use this medication exactly as it was prescribed for you. Do not use it in larger amounts or for longer than recommended by your doctor. Follow the directions on your prescription label.
Varenicline can cause drowsiness, which may impair your thinking or reactions. You may also have mood or behavior changes when you quit smoking. Until you know how varenicline and the smoking cessation process is going to affect you, Be careful if you drive or do anything that requires you to be cautious and alert.
Stop using this medication and call your doctor at once if you have any mood or behavior changes, or if you feel agitated, depressed, or have thoughts about suicide or hurting yourself.
Your family or other caregivers should also be alert to changes in your mood or behavior.
Less serious side effects are more likely, and you may have none at all. Varenicline can cause persistent nausea for up to several months. Talk to your doctor about any side effect that seems unusual or is especially bothersome.
If you miss a dose, use the medication as soon as you remember. If it is almost time for the next dose, skip the missed dose and wait until your next regularly scheduled dose. Do not use extra medicine to make up the missed dose.
There may be other drugs that can interact with varenicline. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.